parseExpr less allocation
diff --git a/rule_parser_test.go b/rule_parser_test.go
index 4adf912..5dc8f24 100644
--- a/rule_parser_test.go
+++ b/rule_parser_test.go
@@ -19,14 +19,6 @@
 	"testing"
 )
 
-func parseExprForTest(e string) Value {
-	v, _, err := parseExpr([]byte(e), nil)
-	if err != nil {
-		panic(err)
-	}
-	return v
-}
-
 func TestRuleParser(t *testing.T) {
 	for _, tc := range []struct {
 		in     string
@@ -109,8 +101,8 @@
 				outputs: []string{"foo"},
 			},
 			assign: &AssignAST{
-				lhs: parseExprForTest("CFLAGS"),
-				rhs: parseExprForTest("-g"),
+				lhs: literal("CFLAGS"),
+				rhs: literal("-g"),
 				op:  "=",
 			},
 		},
@@ -120,8 +112,8 @@
 				outputs: []string{"foo"},
 			},
 			assign: &AssignAST{
-				lhs: parseExprForTest("CFLAGS"),
-				rhs: parseExprForTest("-g"),
+				lhs: literal("CFLAGS"),
+				rhs: literal("-g"),
 				op:  "=",
 			},
 		},
@@ -131,8 +123,8 @@
 				outputs: []string{"foo"},
 			},
 			assign: &AssignAST{
-				lhs: parseExprForTest("CFLAGS"),
-				rhs: parseExprForTest("-g"),
+				lhs: literal("CFLAGS"),
+				rhs: literal("-g"),
 				op:  ":=",
 			},
 		},
@@ -142,8 +134,8 @@
 				outputPatterns: []pattern{pattern{suffix: ".o"}},
 			},
 			assign: &AssignAST{
-				lhs: parseExprForTest("CFLAGS"),
-				rhs: parseExprForTest("-g"),
+				lhs: literal("CFLAGS"),
+				rhs: literal("-g"),
 				op:  ":=",
 			},
 		},